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Nb ‐Doped 0.9 BaTiO 3 –0.1( Bi 0.5 Na 0.5 ) TiO 3 Ceramics with Stable Dielectric Properties at High Temperature
Author(s) -
Yao Guofeng,
Wang Xiaohui,
Wu Yunyi,
Li Longtu
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2011.04793.x
Subject(s) - materials science , microstructure , dielectric , ceramic , grain boundary , doping , precipitation , permittivity , composite material , analytical chemistry (journal) , capacitance , diffusion , ceramic capacitor , mineralogy , capacitor , thermodynamics , electrical engineering , optoelectronics , chemistry , electrode , physics , chromatography , voltage , meteorology , engineering
Nb ‐doped 0.9 BaTiO 3 –0.1 Bi 0.5 Na 0.5 TiO 3 (0.9 BT –0.1 BNT ) ceramics were prepared by conventional solid‐state method. The dielectric and the structural properties were investigated. It was found that the temperature–capacitance characteristics greatly depended on Nb 2 O 5 content. With the addition of 2.0 mol% Nb 2 O 5 , 0.9 BT –0.1 BNT ceramic sample could satisfy the EIA X9R specification. This material was promising for high‐temperature MLCC application. Microstructure element distribution was studied using TEM and EDS . The Bi and Na were almost homogeneously distributed except grain‐boundary segregation of Bi . The Nb exhibited a nonuniform distribution from the grain boundary to the interior, showing the simultaneous presence of Nb ‐rich and Nb ‐poor regions. Such microheterogeneity gave rise to the temperature stability of permittivity. The solution‐precipitation mechanism was introduced to elucidate the evolution of microstructures. Degradation and recovery of insulation resistance were observed under a dc bias at 200°C, which was attributed to the electromigration and diffusion of Na + .